This 32YO female has a known history of an unspecified inherited retinal disease (IRD) diagnosed elsewhere 3-4 years earlier. Genetic testing was negative. She has difficulty seeing in the dark and avoids night driving. More recently, she’s aware of a midperipheral ring of bilateral vision loss. Vision was 20/20 OU.
Optos color RG imaging is fairly normal bilaterally except for drusen-like deposits in the peripheral maculas. Fundus autofluorescence shows a large hyper-FAF ring surrounding each posterior pole, along with a smaller hyper-FAF macular ring. OCT scanning shows outer retinal atrophy sparing the macular center.
Learning Points:
Fundus autofluorescence (FAF) visualizes endogenous fluorophores, compounds that spontaneously fluoresce without an external dye. The main fundus fluorophore is lipofuscin, which resides within the RPE lysosomes. The photoreceptor outer segments absorb some of the autofluorescent excitatory light, and thus normally diminish the FAF signal.
In IRDs, loss of outer segments unmasks this signal, leading to increased FAF. Many patients with an IRD will show a hyper-FAF ring between clinically normal and abnormal retina, which likely represents retina ‘at risk’, showing the junction of a functional and dysfunctional retina (Oishi et al, Int J Retina Vitreous 2019;5(S1);23).
